Buy tickets immediately.
Sale airfares are always subject to change. Every seat on every flight is not offered at the lowest rate.
I recommend starting the search for available seats at Kayak.com vs. calling an airline directly. You can also search for the sale at travel websites such as Expedia, Orbitz or Travelocity, etc.
Airlines can discontinue or pull a sale price without notice when the offer does not have a “ticket-by” date or when the offer is deemed “sold out.”
Clara Bosonetto is a retired travel consultant.